Arizona State University ECN 221 Practice Exam 2 (Ch. 5-7). Contains 30 of the most commonly tested questions and Answers.

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Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A company that bakes chocolate chip cookies av... erages 5.2 chocolate chips per cookie. Assume that the number of chocolate chips per cookie follows the Poisson distribution. What is the probability that a randomly selected cookie will contain one or two chocolate chips? 1) A) 0.1033 B) 0.1697 C) 0.2020 D) 0.0596 2) According to the Deloitte EV Survey, 5% of respondents indicated that they would be willing to pay an extra $500 or more for an electric vehicle versus one with a gasoline engine. A random sample of 25 adults has been selected. Use the Poisson distribution to approximate the binomial distribution to determine the probability that more than two adults from this sample would be willing to pay an extra $500 or more for an electric vehicle versus one with a gasoline engine. 2) A) 0.0859 B) 0.2765 C) 0.3890 D) 0.1316 3) Assume that the number of customers who arrive at a water ice stand follows the Poisson distribution with an average rate of 6.4 per 30 minutes. What is the probability that three or four customers will arrive during the next 30 minutes? 3) A) 0.2365 B) 0.3517 C) 0.2884 D) 0.1888 4) A statistics class at Wilmington College has 25 students of which 15 are math majors and 10 are business majors. The professor randomly selects five students to work together on a group project. What is the probability that none of the students in this group are business majors? 4) A) 0.0230 B) 0.1436 C) 0.1007 D) 0.0565 5) According to the Centers for Medicare & Medicaid Services, 21% of nursing homes in the United States received five stars in overall ratings on a scale of 1 to 5. A random sample of seven nursing homes was selected. What is the probability that exactly three of them received five stars? 5) A) 0.1527 B) 0.0944 C) 0.1263 D) 0.0432 6) The table below shows the numbers of two- to five-bedroom houses in the Belmont neighborhood. Number of Bedrooms Frequency 2 7 3 35 4 56 5 27 What is the probability that a randomly selected house will have 3 or fewer bedrooms? 6) A) 0.572 B) 0.336 C) 0.521 D) 0.475 17) The table below shows the numbers of two- to five-bedroom houses in the Belmont neighborhood. Number of Bedrooms Frequency 2 7 3 35 4 56 5 27 What is the mean number of bedrooms in a house in this neighborhood? 7) A) 4.06 B) 3.82 C) 2.80 D) 2.43 8) According to Bureau of Labor Statistics, 26.0% of the total part-time workforce in the U.S. was between the ages of 25 and 34 during a recent month. A random sample of 90 part-time employees was selected during this quarter. Using the normal approximation to the binomial distribution, what is the probability that exactly 23 people from this sample were between the ages of 25 and 34? 8) A) 0.1615 B) 0.2394 C) 0.0419 D) 0.0951 9) Bananas are sold in bunches at a grocery store and typically consist of 4-8 bananas per bunch. Suppose the weight of these bunches follows a normal distribution with a mean of 3.54 pounds and a standard deviation of 0.63 pounds. What is the probability that a randomly selected bunch of bananas will weigh more than 3.0 pounds? 9) A) 0.8051 B) 0.6950 C) 0.9463 D) 0.5398 10) Costco installs automobile tires on a first-come first-serve basis. The total time a customer needs to wait for the installation to be completed follows the normal distribution with a mean time of 106.3 minutes and a standard deviation of 18.5 minutes. What is the probability that a randomly selected customer will wait more than 125 minutes for his or her tires to be installed? 10) A) 0.2090 B) 0.3409 C) 0.1562 D) 0.4920 11) The ________ probability distribution is bell-shaped and symmetrical. 11) A) uniform B) Poisson C) exponential D) normal 12) The time that customers wait to be served at the delicatessen for a grocery store follows the uniform distribution between 0 and 7 minutes. What is the standard deviation of this distribution? 12) A) 2.02 B) 3.65 C) 4.10 D) 1.16 13) The ________ probability distribution is useful when the majority of the data tend to be in the middle of the distribution. 13) A) exponential B) uniform C) Poisson D) normal 14) Which of the following probability distribution is not continuous? 14) A) exponential B) Poisson C) normal D) All of these are continuous probability distributions. 215) The ________ is used to find the probability that a continuous uniform random variable will fall between two particular values. 15) A) uniform cumulative distribution function B) continuous uniform probability density function C) uniform probability density function D) uniform probability distribution 16) The time for a professor to grade an exam is normally distributed with a mean of 16.3 minutes and a standard deviation of 4.2 minutes. What is the probability that a randomly selected exam will require less than 20 minutes to grade? 16) A) 0.8106 B) 0.9230 C) 0.3715 D) 0.6328 17) Bob's golf score at his local course follows the normal distribution with a mean of 92.1 and a standard deviation of 3.8. The interval around the mean that contains 68% of Bob's golf scores is ________. 17) A) 80.7, 103.5 B) 88.3, 95.9 C) 90.2, 94.0 D) 84.5, 99.7 18) The ________ probability distribution describes data where all the values have the same chance of occurring. 18) A) uniform B) exponential C) normal D) discrete 19) DLP projectors are used in the majority of cinema projection systems and require a special light bulb to display a picture. Assume that the average life of a DLP bulb is 2,000 hours and that this failure time follows the exponential distribution. What is the probability that a randomly selected bulb will last more than 2,500 hours? 19) A) 0.2865 B) 0.2031 C) 0.4492 D) 0.1365 20) Scotland has been a member of the United Kingdom since the 1707 Act of Union. In a recent poll, 38% of Scots would vote in favor of leaving the U.K. A random sample of 135 Scots was selected. What is the probability that between 50 and 60 of them were in favor of leaving the U.K.? 20) A) 0.7245 B) 0.3066 C) 0.5318 D) 0.8810 21) Susan would like to conduct a survey of homeowners in the Meadowbrook neighborhood to get their opinions on proposed road modifications in the area. Which of the following is an example of a stratified sample? 21) A) Susan selects every third house on each street in the neighborhood. B) Susan randomly chooses two streets in the neighborhood and selects every home on these streets. C) Susan selects the first 20 homes that she passes as she walks into the entrance of the neighborhood. D) Susan ensures that her sample contains a number of two-story, split-level, and ranch homes in her sample that corresponds to the number of homes in the neighborhood. 322) A study conducted by Harvard Business School recorded the amount of time CEOs devoted to various activities during the workweek. Meetings were the single largest activity averaging 18 hours per week. Assume that the standard deviation for the time spent in meetings is 5.2 hours. To confirm these results, a random sample of 35 CEOs was selected. This sample averaged 16.8 hours per week in meetings. Which of the following statements is correct? 22) A) The interval that contains 95% of the sample means is 16.3 and 19.7 hours. Because the sample mean is between these two values, we have support for the results of the CEO study by the Harvard Business School. B) The interval that contains 95% of the sample means is 17.1 and 18.9 hours. Because the sample mean is not between these two values, we do not have support for the results of the CEO study by the Harvard Business School. C) The interval that contains 95% of the sample means is 15.7 and 20.3 hours. Because the sample mean is between these two values, we do not have support for the results of the CEO study by the Harvard Business School. D) The interval that contains 95% of the sample means is 15.7 and 20.3 hours. Because the sample mean is between these two values, we have support for the results of the CEO study by the Harvard Business School. 23) Suppose the local Best Buy store averages 483 customers per day entering the facility with a standard deviation of 112 customers. A random sample of 48 business days was selected. What is the probability that the average number of customers in the sample is between 480 and 500? 23) A) 0.2521 B) 0.1579 C) 0.3377 D) 0.4284 24) Taylor's Mill is a neighborhood comprised of 185 homes. According to the website Zillow, the average market value of the homes in this neighborhood is $418,300 with a standard deviation of $36,500. What is the standard error for a random sample of 32 homes from this neighborhood? 24) A) $5,883.76 B) $7,510.35 C) $4,153.87 D) $6,452.35 25) MFP Research reported that average apartment rent in the U.S. is $1,083. A random sample of 39 apartments was selected. Using a population standard deviation of $227, what is the probability that the sample mean will be greater than $1,035? 25) A) 0.9066 B) 0.7060 C) 0.8319 D) 0.7557 26) Suppose there are 310 first-year lawyers in a particular metropolitan area with an average starting salary of $156,000 and a standard deviation of $13,000. What is the standard error of the mean for a random sample of 33 first-year lawyers? 26) A) $3,145.44 B) $2,263.01 C) $4,512.26 D) $2,142.63 27) Recently, FHA mortgages, which are insured by the federal government, accounted for 28% of all home-purchase mortgages that were approved. A random sample of 150 mortgage applications was selected. What is the probability that 48 or more from this sample were insured by the FHA? 27) A) 0.1379 B) 0.3974 C) 0.2291 D) 0.1915 28) In ________ sampling, every kth member of the population is chosen for the sample. 28) A) probability B) nonprobability C) systematic D) cluster 429) The average battery life of the iPhone 4S is reported to be 7.0 hours. Assume that the standard deviation for the battery life for this cell phone is 45 minutes. A random sample of 38 iPhones had an average battery life of 6.5 hours. Which of the following statements is correct? 29) A) The interval that contains 95% of the sample means is 5.50 and 8.50 hours. Because the sample mean is between these two values, we have support that the average battery life equals 7.0 hours. B) The interval that contains 95% of the sample means is 5.50 and 8.50 hours. Because the sample mean is between these two values, we do not have support that the average battery life equals 7.0 hours. C) The interval that contains 95% of the sample means is 6.76 and 7.24 hours. Because the sample mean is not between these two values, we do not have support that the average battery life equals 7.0 hours. D) The interval that contains 95% of the sample means is 6.76 and 7.24 hours. Because the sample mean is not between these two values, we have support that the average battery life equals 7.0 hours. 30) Suppose the average math SAT score for students enrolled at Madison College is 507.3 with a standard deviation of 68.2. A random sample of 49 students has been selected. The standard error of the mean for this sample is ________. 30) A) 68.2 B) 10.4 C) 38.4 D) 7.1 31) The Central Limit Theorem plays an important role in statistics because it provides information about the shape of the 31) A) sampling distribution for any sample size. B) sampling distribution when the sample size is sufficiently large. C) population distribution when the sample size is sufficiently large. D) population distribution for any sample size. 32) Susan would like to conduct a survey of homeowners in the Meadowbrook neighborhood to get their opinions on proposed road modifications in the area. Which of the following is an example of a simple random sample? 32) A) Susan selects the first 20 homes that she passes as she walks into the entrance of the neighborhood. B) Susan selects every third house on each street in the neighborhood. C) Susan randomly chooses two streets in the neighborhood and selects every home on these streets. D) None of these choices describes a simple random sample. TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 33) A listing of all the possible outcomes of an experiment for a discrete random variable along with the relative frequency of each outcome is called a discrete probability distribution. 33) 34) The number of successes in a binomial experiment must range from zero to n. 34) 35) The hypergeometric distribution is used when samples are taken from an infinite population with replacement. 35) 536) The probability of a binomial distribution represents the variation that we would see in the number of successes over n trials, assuming the chance of a success is p. 36) 37) The mathematical expression that describes the shape of the uniform distribution is known as the continuous uniform probability density function. 37) 38) Sampling error is the difference between a sample statistic and a population parameter. 38) 39) The higher the standard error of the mean, the less variation you will notice from one sample mean to the next as they are drawn from the population. 39) 40) An Internet poll, where individuals may respond to a survey as many times as they choose to, is an example of a nonprobability sample. 40) 6Answer Key [Show More]

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